1. Volume 6, Issue 6, Pages 940-956 (June 2016)
Sepsis Induces Hematopoietic Stem Cell Exhaustion and Myelosuppression through Distinct Contributions of TRIF and MYD88 
Huajia Zhang, Sonia Rodriguez, Lin Wang, Soujuan Wang, Henrique Serezani, Reuben Kapur, Angelo A. Cardoso, Nadia Carlesso 
Stem Cell Reports 
Volume 6, Issue 6, Pages (June 2016)
DOI: /j.stemcr
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2. Stem Cell Reports 2016 6, 940-956DOI: (10.1016/j.stemcr.2016.05.002)
Copyright © 2016 The Authors Terms and Conditions

3. Figure 1
LPS and Sepsis Induce HSC Expansion in a TRIF-Dependent Manner
Immunophenotypic analysis of BM cells was conducted by fluorescence-activated cell sorting (FACS) on WT, MYD88−/−, and TRIF−/− mice 24 hr after challenge with LPS or PBS, or CLP surgery.
(A and B) Representative contour plots for LSK populations (A) or HSPC (B) labeled with SLAM marker (LT-HSC: Lin−SCA-1+c-KIT+CD150+CD48−; MPP1: Lin−SCA-1+c-KIT+CD150+CD48+; MPP2: Lin−SCA-1+c-KIT+CD150−CD48+).
(C–F) Average frequency of LSK (C), LT-HSC (D), MPP1 (E), and MPP2 (F) in the gated Lin− population (left) and average absolute cell number per femur of each subset (right) in PBS- versus LPS-challenged mice (n = 5–14).
(G) Average absolute number of cells per femur in CLP-challenged versus sham-treated mice in BM subsets, from left to right: LSK, LT-HSC, MPP1, and MPP2 (WT: n = 6–11; MYD88−/− and TRIF−/−: n = 3–5).
Data represent mean ± SEM. LPS versus PBS: ∗p < 0.05, ∗∗p < 0.01; WT versus MYD88−/− or TRIF−/−: ˆp < 0.05, ˆˆp < 0.01.
Stem Cell Reports 2016 6, DOI: ( /j.stemcr )
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4. Figure 2
Role of SCA-1 Re-expression, Cell-Cycle Activation, and Cell Survival in LSK Expansion following LPS
(A and B) Lys-GFP reporter mice were challenged with LPS or PBS and their BM analyzed by FACS at 24 hr. (A) Representative density plots for Lys-GFP and FCγR expression on GMP, CMP, LSK, LT-HSC, and MPP subsets in the BM. (B) Absolute number per femur of total (red), FCγR+ (purple), and Lys-GFP+ (green) cells in LSK (left), LT-HSC (middle), and MPP (right) subsets (n = 3–4).
(C–E) Analysis of the BM after 24 hr of LPS or PBS challenge in WT, TRIF−/−, and MYD88−/− mice. (C) Representative contour plots (left) showing S phase (as bromodeoxyuridine incorporation) and G0/G1 phase for the LSK population. Bar graph (right) indicates the mean LSK distribution in S phase and G0 phase (n = 16–20). (D) Bar graphs show the percentage of cells in S phase in LT-HSC, MPP1, and MMP2 (n = 7–10). (E) Bar graphs show the percentage of annexin V+ cells in LSK, LT-HSC, MPP1, and MMP2 (n = 3–5).
Data represent mean ± SEM. LPS versus PBS: ∗p < 0.05, ∗∗p < 0.01; WT versus MYD88−/− or TRIF−/−: ˆˆp < 0.01.
Stem Cell Reports 2016 6, DOI: ( /j.stemcr )
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5. Figure 3
LPS and Sepsis Induce BM Myeloid Suppression in an MYD88-Dependent Manner
Immunophenotypic analysis of BM cells was conducted by FACS on WT, MYD88−/−, and TRIF−/− mice 24 hr after challenge with LPS or PBS, or CLP surgery.
(A) Representative contour plots of myeloid progenitor populations labeled with the progenitor markers (CMPs: Lin−IL-7Rα−SCA-1−c-KIT+CD34+FCγRlo; GMPs: Lin−IL-7Rα−SCA-1−c-KIT+CD34+FCγRhi; MEPs: Lin−IL-7Rα−SCA-1−c-KIT+CD34−FCγRlo).
(B) Representative contour plots of mature myeloid GR1+MAC1+ cells.
(C–E) Average frequency (top) of CMP (C) and GMP (D) in the gated Lin− population and of GR1+MAC1+(E) in the total BM population, and average absolute cell number per femur of each subset (bottom) in PBS- versus LPS-challenged mice (n = 5–14).
(F) Bar graphs indicate the mean of absolute number of CMP, GMP, and GR1+MAC1+ per femur in mice subjected to CLP- versus sham-treated mice (WT and MYD88−/−: n = 6–10; TRIF−/−: n = 3).
Data represent mean ± SEM. LPS versus PBS: ∗p < 0.05, ∗∗p < 0.01; WT versus MYD88−/− or TRIF−/−: ˆp < 0.05, ˆˆp < 0.01.
Stem Cell Reports 2016 6, DOI: ( /j.stemcr )
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6. Figure 4
Cell-Autonomous and Non-cell-autonomous Roles of TRIF and MYD88 in LPS-Induced HSC Expansion and Myelosuppression
(A) Chimeras: WT recipients of TRIF−/− donor cells, TRIF−/− recipients of WT donor cells, and WT recipients of WT cells were challenged with LPS or PBS and analyzed after 24 hr (n = 4). WT and TRIF−/− mice (parental) were used as a reference (n = 11). Bar graph shows the mean percentage of LT-HSC and MPPs in the Lin− population.
(B) WT recipients (CD45.1) were transplanted with WTGFP+ + MYD88−/− BM cells or WTGFP+ + TRIF−/− BM cells, mixed 1:1 ratio. After 8 weeks mice were challenged with LPS or PBS for 24 hr. Bar graphs show the mean percentage of LT-HSC and MPPs in gated WTGFP+ donor cells (light and dark gray bars, n = 4) and in gated GFP− (CD45.2) KO donor cells (red and black bars, n = 4) within the same recipient.
(C) Bar graph shows the percentage of CMP and GMP in LPS- versus PBS-treated mice: in chimeras WT recipients of TRIF−/− or MYD88−/− cells, TRIF−/− and MYD88−/− recipients of WT cells, and in parental WT, MYD88−/−, and TRIF−/− mice. Parental, n = 8–19; chimeras, n = 4–6.
(D) WT recipients of MYD88−/− donor cells, MYD88−/− recipients of WT donor cells, and parental WT and MyD88−/− mice were challenged with LPS or PBS and analyzed after 24 hr. Bar graph shows the mean percentage of GR1+MAC1+ cells in total BM cells (n = 8–17).
(E) WT recipients (CD45.1) were transplanted with WTGFP+ + MYD88−/− BM cells or WTGFP+ + TRIF−/− BM cells, mixed 1:1 ratio. After 8 weeks mice were challenged with LPS or PBS for 24 hr. Bar graphs show the mean percentage of GR1+MAC1+ cells in in gated WTGFP+ donor cells (WT; n = 4) and in gated GFP− (CD45.2) KO donor cells (KO, n = 4) within the same recipient. PBS controls are WT-GFP+ of all chimeras challenged with PBS (n = 8).
(F) LPS activation of TLR4-MYD88 or -TRIF signaling exerts its effects on hematopoietic cells (HC) through direct and indirect mechanisms: (1) microenvironment-dependent: activation of MYD88 in the BM stroma cells results in the release of factors that act on HC; (2) hematopoietic-restricted: activation of MYD88 in HC stimulates the release of factors affecting neighboring HC in a paracrine fashion; (3) cell-intrinsic (or cell-autonomous): activation of TRIF in the HC causes a direct effect on the cell.
Data represent mean ± SEM. LPS versus PBS: ∗p < 0.05, ∗∗p < 0.01; WT versus MYD88−/− or TRIF−/−: ˆp < 0.05, ˆˆp < 0.01.
Stem Cell Reports 2016 6, DOI: ( /j.stemcr )
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7. Figure 5 Loss of MYD88 but Not TRIF Preserves Myeloid Differentiation
(A) Purified Lin− cells were cultured with PBS or LPS in vitro and analyzed 12 hr later. Bar graphs show the percentage of LSK, MP (CMP + GMP) in Lin− cells, and GR1+MAC1+ in total alive cells (n = 6).
(B and C) CMP and GMP subsets were sorted from WT, TRIF−/−, and MYD88−/− mice exposed to LPS or PBS for 24 hr. Sorted cells were cultured in vitro in myeloid differentiation conditions. Representative contour plots (left) and average percentage (right) of GR1+MAC1+ cells generated from CMPs at day 4 (B) and from GMPs at day 2 (C) (n = 3–4).
Data represent mean ± SEM. LPS versus PBS: ∗p < 0.05, ∗∗p < 0.01; MYD88−/− versus WT or TRIF−/−: ˆˆp < 0.01.
Stem Cell Reports 2016 6, DOI: ( /j.stemcr )
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8. Figure 6
Loss of TRIF Preserves Long-Term Engraftment and Stem Cell Self-Renewal after Acute LPS Exposure
(A and C–E) 2,500 LSK cells sorted from PBS- or LPS-challenged WT, MYD88−/− and TRIF−/− mice (CD45.2+) were transplanted into recipient BoyJ (CD45.1+) and monitored for up to 24 weeks.
(A) Left: PBS LSK (400–500 LSKCD150+CD48−) donor cell engraftment (CD45.2+) in the peripheral blood. n = 8–12. Right: LPS LSK (200 LSKCD150+CD48−) donor cell engraftment (CD45.2+) in the peripheral blood. WT, n = 5–14; MyD88−/−, n = 6–12; TRIF−/−, n = 7–8.
(B) Percentage of CD45.2+ cells in the BM of CD45.1+ BoyJ mice 16 hr after receiving 25,000 LSK cells sorted from LPS- or PBS-challenged WT (CD45.2+) mice (n = 3).
(C) Percentage of donor engraftment of WT, MYD88−/−, and TRIF−/− PBS or LPS LSK cells (CD45.2+) in the BM of recipient mice at 24 weeks post transplantation (n = 7–9).
(D) Percentage of donor-derived CD45.2+ BM LT-HSC, MPP1, and MPP2 subsets in recipient mice (n = 7–9).
(E) Absolute number of donor-derived LT-HSC per femur: in WT, MYD88−/−, and TRIF−/− mice at steady state, prior BM harvest for transplants (parental); at 24 weeks in transplanted recipients of sorted LSK cells from PBS-challenged mice (TR-PBS); and of sorted LSK cells from LPS-challenged mice (TR-LPS). n = 7–9.
(F) Self-renewal quotients of LT-HSC cells from PBS- and LPS-challenged WT, MYD88−/−, and TRIF−/− mice at 24 weeks post transplantation. Quotient is calculated by dividing the absolute number of LT-HSC at 24 weeks by the average number of LT-HSC input at the time of transplantation. n = 7–9.
Data were from two independent experiments and represent mean ± SEM. LPS versus PBS: ∗p < 0.05, ∗∗p < 0.01; WT versus MYD88−/− or TRIF−/−: ˆp < 0.05, ˆˆp < n.s., not significant.
Stem Cell Reports 2016 6, DOI: ( /j.stemcr )
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9. Figure 7
Impact of LPS on Multilineage Reconstitution and on of PU.1 and CEBP/α
(A and B) 2,500 LSK cells sorted from PBS- or LPS-challenged WT, MYD88−/−, and TRIF−/− mice (CD45.2+) were transplanted into recipient BoyJ (CD45.1+). Recipients were monitored for up to 24 weeks.
(A) Percentage of donor-derived CD45.2+ BM CMP (left), GMP (middle), and GR1+ (right) in recipient mice at week 24 (n = 7–9).
(B) Line graphs show mean percentage of donor CD45.2+ cells in in myeloid cells (GR1+), B cells (B220+), and T cells (CD4+ or CD8+) in peripheral blood of recipient mice after transplantation (n = 7–16).
(C) Relative mRNA expression level of Spi1 and CebpA in LSK cells sorted from WT (n = 5–9 samples), MYD88−/− (n = 4–5 samples), and TRIF−/− (n = 3 samples) mice challenged with PBS or LPS for 24 hr; each sample derived from cells pooled from 2–3 mice; minimum of three independent experiments.
(D) WT, MYD88−/−, and TRIF−/− LSK cells were sorted at 24 weeks after transplantation. Fold change of expression level of Spi1 and CebpA (n = 3–4 samples derived from cells pooled from 2–3 mice).
(E) Working model. TRIF and MYD88 uncouple the effects of TLR4-mediated injury on hematopoietic stem cells and myeloid progenitors during severe sepsis. The role of TLR4 in regulating hematopoiesis in homeostatic conditions is still unclear. It is possible that the gut microbiota maintains a systemic basal state of TLR4 activation. In the state of severe sepsis, maximal activation of TLR4 by bacterial LPS activates: (1) TRIF, leading to injury of LT-HSC (Figure 6) and dysfunctional expansion of MPPs by cell-cycle activation, shift of progenitors re-expressing SCA-1, and impaired egress (Figures 1E, 1F, 2, 7A, and 7B); and (2) MYD88, resulting in damage of myeloid progenitors by increased apoptosis and impaired differentiation (Figures 3 and 5). Cell-autonomous and non-cell-autonomous mechanisms contribute to these effects in both pathways (Figure 4).
Data represent mean ± SEM. LPS versus PBS: ∗p < 0.05, ∗∗p < 0.01; WT versus MYD88−/− or TRIF−/−: ˆp < 0.05, ˆˆp < 0.01.
Stem Cell Reports 2016 6, DOI: ( /j.stemcr )
Copyright © 2016 The Authors Terms and Conditions